Freezing Light in it’s Tracks

Light is thought to be the fastest stuff around, zipping so speedily through the universe that, even if it were tangible, you probably couldn’t pin it down. But in September, physicists reported the seemingly impossible: They froze light into a crystal-like state.

Light particles, or photons, normally interact only with matter, not each other. But Princeton physicist Andrew Houck and colleagues built a device that effectively lets one photon trade energy with another, thereby freezing light in it’s tracks…